To first create and then try convert line graphics is not necessary. The approach I used for similar task was to create directly lines from the points and bearing (I used azimuth and constant distance) in QGIS.
- for every point get x2 and y2 coordinates of the line end point - from (starting) point X and Y, azimuth and your preferable distance. That can be done with field calculator using expression or if something more advanced needed function editor tab.
In my case the expression was:
x2 = $x + "distance" * sin(("azimuth" + 90)* $pi/180)
y2 = $y + "distance" * cos(("azimuth" + 90)* $pi/180)
- with field calculator again create column named WKT which contains following string:
LINESTRING (x1 y1,x2 y2)
Following written above it should look like:
WKT = 'LINESTRING (' || to_string($x) || ' ' || to_string($y) || ',' || to_string("x2") || ' ' || to_string("y2") || ')'
By x1 y1 x2 y2 is meant your line starting and ending coordinates. Save as csv and add saved file to map. QGIS should recognise the WKT column as line geometry column and create lines for every source point. After that you can save it as line shapefile or in many other formats.